docs/vm: rename documentation files to .rst

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 0 insertions, 186 deletions

diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt
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-.. hwpoison:
-
-========
-hwpoison
-========
-
-What is hwpoison?
-=================
-
-Upcoming Intel CPUs have support for recovering from some memory errors
-(``MCA recovery``). This requires the OS to declare a page "poisoned",
-kill the processes associated with it and avoid using it in the future.
-
-This patchkit implements the necessary infrastructure in the VM.
-
-To quote the overview comment:
-
- * High level machine check handler. Handles pages reported by the
- * hardware as being corrupted usually due to a 2bit ECC memory or cache
- * failure.
- *
- * This focusses on pages detected as corrupted in the background.
- * When the current CPU tries to consume corruption the currently
- * running process can just be killed directly instead. This implies
- * that if the error cannot be handled for some reason it's safe to
- * just ignore it because no corruption has been consumed yet. Instead
- * when that happens another machine check will happen.
- *
- * Handles page cache pages in various states. The tricky part
- * here is that we can access any page asynchronous to other VM
- * users, because memory failures could happen anytime and anywhere,
- * possibly violating some of their assumptions. This is why this code
- * has to be extremely careful. Generally it tries to use normal locking
- * rules, as in get the standard locks, even if that means the
- * error handling takes potentially a long time.
- *
- * Some of the operations here are somewhat inefficient and have non
- * linear algorithmic complexity, because the data structures have not
- * been optimized for this case. This is in particular the case
- * for the mapping from a vma to a process. Since this case is expected
- * to be rare we hope we can get away with this.
-
-The code consists of a the high level handler in mm/memory-failure.c,
-a new page poison bit and various checks in the VM to handle poisoned
-pages.
-
-The main target right now is KVM guests, but it works for all kinds
-of applications. KVM support requires a recent qemu-kvm release.
-
-For the KVM use there was need for a new signal type so that
-KVM can inject the machine check into the guest with the proper
-address. This in theory allows other applications to handle
-memory failures too. The expection is that near all applications
-won't do that, but some very specialized ones might.
-
-Failure recovery modes
-======================
-
-There are two (actually three) modes memory failure recovery can be in:
-
-vm.memory_failure_recovery sysctl set to zero:
-	All memory failures cause a panic. Do not attempt recovery.
-	(on x86 this can be also affected by the tolerant level of the
-	MCE subsystem)
-
-early kill
-	(can be controlled globally and per process)
-	Send SIGBUS to the application as soon as the error is detected
-	This allows applications who can process memory errors in a gentle
-	way (e.g. drop affected object)
-	This is the mode used by KVM qemu.
-
-late kill
-	Send SIGBUS when the application runs into the corrupted page.
-	This is best for memory error unaware applications and default
-	Note some pages are always handled as late kill.
-
-User control
-============
-
-vm.memory_failure_recovery
-	See sysctl.txt
-
-vm.memory_failure_early_kill
-	Enable early kill mode globally
-
-PR_MCE_KILL
-	Set early/late kill mode/revert to system default
-
-	arg1: PR_MCE_KILL_CLEAR:
-		Revert to system default
-	arg1: PR_MCE_KILL_SET:
-		arg2 defines thread specific mode
-
-		PR_MCE_KILL_EARLY:
-			Early kill
-		PR_MCE_KILL_LATE:
-			Late kill
-		PR_MCE_KILL_DEFAULT
-			Use system global default
-
-	Note that if you want to have a dedicated thread which handles
-	the SIGBUS(BUS_MCEERR_AO) on behalf of the process, you should
-	call prctl(PR_MCE_KILL_EARLY) on the designated thread. Otherwise,
-	the SIGBUS is sent to the main thread.
-
-PR_MCE_KILL_GET
-	return current mode
-
-Testing
-=======
-
-* madvise(MADV_HWPOISON, ....) (as root) - Poison a page in the
-  process for testing
-
-* hwpoison-inject module through debugfs ``/sys/kernel/debug/hwpoison/``
-
-  corrupt-pfn
-	Inject hwpoison fault at PFN echoed into this file. This does
-	some early filtering to avoid corrupted unintended pages in test suites.
-
-  unpoison-pfn
-	Software-unpoison page at PFN echoed into this file. This way
-	a page can be reused again.  This only works for Linux
-	injected failures, not for real memory failures.
-
-  Note these injection interfaces are not stable and might change between
-  kernel versions
-
-  corrupt-filter-dev-major, corrupt-filter-dev-minor
-	Only handle memory failures to pages associated with the file
-	system defined by block device major/minor.  -1U is the
-	wildcard value.  This should be only used for testing with
-	artificial injection.
-
-  corrupt-filter-memcg
-	Limit injection to pages owned by memgroup. Specified by inode
-	number of the memcg.
-
-	Example::
-
-		mkdir /sys/fs/cgroup/mem/hwpoison
-
-	        usemem -m 100 -s 1000 &
-		echo `jobs -p` > /sys/fs/cgroup/mem/hwpoison/tasks
-
-		memcg_ino=$(ls -id /sys/fs/cgroup/mem/hwpoison | cut -f1 -d' ')
-		echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg
-
-		page-types -p `pidof init`   --hwpoison  # shall do nothing
-		page-types -p `pidof usemem` --hwpoison  # poison its pages
-
-  corrupt-filter-flags-mask, corrupt-filter-flags-value
-	When specified, only poison pages if ((page_flags & mask) ==
-	value).  This allows stress testing of many kinds of
-	pages. The page_flags are the same as in /proc/kpageflags. The
-	flag bits are defined in include/linux/kernel-page-flags.h and
-	documented in Documentation/vm/pagemap.txt
-
-* Architecture specific MCE injector
-
-  x86 has mce-inject, mce-test
-
-  Some portable hwpoison test programs in mce-test, see below.
-
-References
-==========
-
-http://halobates.de/mce-lc09-2.pdf
-	Overview presentation from LinuxCon 09
-
-git://git.kernel.org/pub/scm/utils/cpu/mce/mce-test.git
-	Test suite (hwpoison specific portable tests in tsrc)
-
-git://git.kernel.org/pub/scm/utils/cpu/mce/mce-inject.git
-	x86 specific injector
-
-
-Limitations
-===========
-- Not all page types are supported and never will. Most kernel internal
-  objects cannot be recovered, only LRU pages for now.
-- Right now hugepage support is missing.
-
----
-Andi Kleen, Oct 2009